Method of striking and maintenance of an electric arc in alpha medium having alpha great dielectric strength



@cfi. W, 1933. J. BETHENOD METHOD OF STRIKING AND MAINTENANCE OF AN ELECTRIC ARC IN A MEDIUM HAVING A GREAT DIELECTRIC STRENGTH Filed Jan. 16, 1932 Inventor y 17% Attorneys Patented Oct. 17, 1933 ItIETHOD 0F STG AND MA1NTENAN3E OF AN ELECTRIC ARC IN A MEDIUM HAV- ING A GREAT DIELECTRIC STRENGTH Joseph Bethenod, Paris, France, assignor to LAir Liqulde Societe Anonyme Pour LEtude et LExploitation Des Procedes Georges Claude, Paris, France Application i sues is, 1932; Serial No. scarce; and in Germany Januaryl'LiQtll 6 Claims. o]; 204- 1 Ithas already been proposed to utilize the very c a ed t u h a spas s. itis thus nee great rise 01' temperature produced locally by to add to the installation a special general an electric arc to eflect certain chemical reacpable of ensuringthe discharge in quest tlons in a medium possessing great dielectric the desired frequency. Furthermore, as ti 5 strength, such as a liquid hydrocarbon. Due to plications particularly in view always corre the insulating properties of suchamedium, the to the use-in the arc itself of considerable 1 production and maintenance of an electric at the presence of this auxiliary generator do vpresents serious difliculties, especiallyit'alterform any appreciable inconvenience, its hating current is used; whichotherwise possesses being limited to a fraction oi'- the power sp 0 the advantage elf-easily attainingthenecessary the arc to: produce the desired thermal "voltage by means of strong and simple apparatus Under these conditions, an installation a Lhavlng no collector. Numerous tests have shown i s qth -inv ntion may be constituted i that his only possible to obtain stable operation cordance with the accompanying diagram when a no-load voltage is avaflable which is four drawing which illustrates an example of ti l to five times higher thanthe load voltage between vention. It is to be assumed that the arc the electrodes. To realize such a diirerencebemaintained. is to b striked between electn tween thesetwo'volta'ges, it is possibleleither to and 2 in a medium having great diel interpose, in the known manner, between the supen th, such as a liquid hydrocarbon, coni ply mains and the arc a-suitably dimensioned self in a metal reservoir 3. This are is s'uppli induction coil or to "utilize as the independent an alternator 4 of industrial frequency, th source of supply an alternator-having a very high tential drop of which has been suitably 01 potential d I 3 The electrode 2 is earthed to the container 1. But, even with this latter method of supply, apsup rcuit being mplet d y th a paratus must necessarily .be used, the nominal whichisearthed at G. As the auxiliary gem 3 power of. which is much greater the power there is'usedan alternator I ofirmusicalireq' aotuall alisorbed'in the are, so that-it is dimcuit f r ampl 50 t 0 p 's p s to realize economically'aninstallation having an w i pp s. the primary of a-transforn acceptable -efliciency. It has been discovered the secondary 0f WhiGh-iS connected on th 'that a much more satisfactory solution ,irom an, hand to one of the terminals of a condenser 39 industrial point'of view consists in using between. on the other hand to the bodyoi a metal b the electrodes in order to stabilize the are, a which contains a rotary spark; gap, the rot series of oscillating discharges, permanently ot-which rotates synchronously with that c sparking over between the electrodes. This alternator 7. The box iii, the use of whicl method, however, known under the term of "the be explained later, is itself connected witl pilot spark", only gives entirely satisfactory recable 5' and the earth 6; on the other ham 4 suits in allrespects when using certainarrange il'xed electrode 12 is also earthed, while th ments which form the subject of the present insula'ted electrode iii-is connected to the pi vention. Experience. shows-that with these arthe transformer it which isc'onnected to 01 rangements theno-loadvoltage necessary for-enthe terminals of the condenser 9. The 1 cellent stability doesnot generally exceed twice terminals of the condenser 9 is connects theload voltage between electrodsra still lower means of an insulated cable 14 to the insu no-load voltage may even be used in certain electrode 1 of the container 3. It is easy cases.' In any case, the nominal power required understood thatthe condenser 9 is charger tor. electrical ap aratus is always considerably riodically by the condenser 7, the'charging f reduced with respectto that n'where the cult being completed by the principal at or pilot spark is not used. .To obtain the result in cable lathe-alternator i, and the w 11 question,- theilrstconditionis to obtain per sec- 5, 6. With regard to the periodic disch and a number or oscillating discharges which is through the gap which separates the electrm relatively high multiple of the frequency or the and 2, this is ensured by the passage of the 1 .t alternating current supplied to the are. It, forof the rotor 1.1 in front of the fixed electrcdi example; this latter frequency reaches 50'pericds and 13. Each passage determines two $11 per second, good resultsare obtained with a i 4 taneous sparks lumping respectively. beti thousand discharges per second.- These. diseach or these electrodes c h arges being produced in the known manner by tooth of the rotor 11, thus producing a- IJBZ'iOl 3 the perlodiccharge of a condenser which holis- .short circuiting or the se condary of the tr ier 8. At each short circuit, the voltage at terminals oiithe condenser 9 is suddenly sferred between the electrodes 1 and 2, be- :n' which it is discharged ii the voltage in tion is sufiiciently high. Naturally, known us (not shown) are provided to suitably reguthe angular position or the teeth of the rotor rith respect to the poles of the rotor of the mator 7. On the other hand, the number of barges persecond depends on the number aeth of the rotor 11; it will generally be either l1 to or double the frequency'of the alternator It should be noted that the use of a rotary "k gap is particularly advisable in the present E, as it is a question of ensuring regularly a as of discharges of relatively high energy folng each other at very short intervals over working periods compatible with commercial king. The permanent production of very rgetic oscillating discharges might present in :tice serious inconveniences owing to the elecnagnetic radiation which they may create. s radiation might, on the oneihand, interfere n inadmissible manner. with the radio-electric livers of the neighbourhood, and on the other id, provoke the formation of coronas at v'aripoints oi'the installation; these coronas may omevery dangerous when the installation is :nded for the production of inflammable gases. ording to one of the characteristics of the sent invention, these defects are completely ided on the one hand by arranging the rotary rking gap 11 inc. metal box which forms a aen, and on .the other hand, by surrounding the le 14 by al'metal tube 16 which constitutes connection between the box 10 and the earthcable 5. Due to this arrangement which y be completed if necessary by a metal hood rounding the high tension. terminal supporttheelectrode 1, any troublesomeor dangerous :tromagnetic radiation is practically supssed. On the other hand, a reactance coil 17 erted in the cable protects the alternator 4 liIlSt the passage of high frequency currents, s protection is completed on the drawing by ondenser 18, connected to the terminals of the arnator 4 as also an ohmic resistance 19 in sei with a sparking gap 20. The latter system vvides a very convenient. method-of ensuring it the alternator 4 is not subjected to dangerr excess voltages. Finally, the. case 10 is pref! .bly providedwith a fan 21. driven by any table means which renews atmosphere of the :e, the vitiated air escaping by.-the outlet 22.

It is evident that the invention'covers' varians in particular as regards the means of pro- :ing the pilot spark between the electrodes of 2 vessel 3; any other combination of high freency circuits, might be used based on condin that a seriesof discharges can be furnished zirequency of which is a high multiple of the quency oi the principal alternator 4. In consion,-the invention obviously extends to the ie where the source of supply of the arc is a lyph one and furnishes either several monoase' arcs, or one polyphase arc.

What I claim is:

l'. A method of striking and maintaining an ctric are between two electrodes situated in .a :dium' having great dielectric strength, wherethe arc is striked and maintained between the ctrodes by means of a pilot spark formed by succession of high frequency discharges. the :qucncy of succession of these discharges becharge of the condenser across the said elecing of the magnitude order of a musical frequency.

2; An apparatus for striking and maintaining an electric are between two electrodes situated in a medium having a great dielectric strength which comprises a source of electrical current connected to said electrodeaan auxiliary circuit comprising a condenser, the said electrodes being connected to said auxiliary circuit, means for charging the said condenser and means for dis- .charging said condenser across the said electrodes trodes.

4. An apparatus for striking and maintaining an electric are between two electrodes situatedin a medium having a great. dielectric strength which comprises-a source of alternating current of low frequency connected to said electrodes, an

auxiliary'circuit comprising a condenser, the said electrodes being connected to said auxiliary circuit, an alternator of a frequency at least ten times higher than the frequency. of the first named source of alternating current for charging the condenser and means for'discharging the condenser across the said electrodes.

5. An apparatus for striking and maintaining an electric are between two electrodes situated in a medium having a great dielectric strength which comprises a. source of electrical current connected to said electrodes, an auxiliary circuit comprising a condenser, the said electrodes being connected to said. auxiliary circuit, an alternator of musical frequency distinct from the said source of electrical. current for charging the condenser, a rotary spark gap rotating synchronously with the said alternator for the discharged the condenser across said electrodes and a metal case enclosing spark gap to suppress electromagnetic radiations outside.

. 6. An apparatus for striking and maintaining an electric are between two electrodes situated in a medium having a great dielectric strength which comprises a source of electrical current connected to said electrltuies, an auxiliary circuit comprising a condenser, the said electrodes being. connected to said aimiliary circuit, an alternator of musical frequency distinct from the said source of electrical current for charging the condenser, arot-ary spark. gap rotating synchronoua ly with the said alternator for. the discharge of the condenser across the said electrodes, a metal case enclosing said sparlr gap to suppress electromagnetic radiations outside and a metal tube fixed to the metal case and surrounding thecable leading from one pole of. the condenser to' the insulated electrode in the metal container for the medium oi great dieletcric strength substantiallyover the whole length of said leading cable, this container and the said metal case beingearthed.'-

JOBEPH BETHENOD. 

